LogisimRevisited

Manual

Logisim AI Circuit Coach & Signal Prover

How Logisim AI works: deterministic 4-stage Socratic circuit coaching, automated truth-table verification, and the "Why is this wire 0, 1, E, or Z?" backward signal prover.

Logisim AI in Logisim Revisited is a symbolic, deterministic reasoning engine built directly into the circuit simulator—not an LLM chatbot that guesses or hallucinates. Because it analyzes your live netlist and 4-state signal graph directly in the browser, every explanation is 100% faithful to your circuit and works completely offline.

Four-Stage Socratic Coaching ("Coach me")

When a circuit does not match the target truth table or behaves unexpectedly, open the AI Coach drawer and choose Coach me. Instead of giving away the entire solution at once, the coach reveals help in four progressive stages so you can stop as soon as the idea clicks:

  1. 1. Where to look: Highlights the specific component, pin, or net where the discrepancy or wiring error originates (such as an unconnected input pin or a short-circuit bus).
  2. 2. The pattern: Identifies the category of digital logic issue—for example, competing drivers on a Tunnel net, an inverted Carry chain in a Full Adder, or a wrong pin order on a 7-Segment Display.
  3. 3. The logic: Shows the exact input combination (truth-table row) where your circuit’s actual output diverges from the expected Boolean output, or traces the controlling input on an AND, OR, or XOR Gate.
  4. 4. Conclusion: Explains the concrete fix needed to repair the circuit.

"Why is this wire 0, 1, E, or Z?" Signal Prover

Click any wire, Pin, Probe, flip-flop (S-R, T, J-K, or D Flip-Flop), or gate on the schematic and ask Why? The backward signal provenance tracer walks upstream from that point through every gate and net that determines its current state:

  • Why is this 0 or 1? Traces the active driving gate and highlights whether a controlling input (such as a single 0 on an AND gate or 1 on an OR gate) determined the output.
  • Why is this E (red conflict)? Pinpoints the two or more competing outputs driving 0 and 1 onto the same wire simultaneously, or identifies the upstream floating/invalid input propagating an error. Try it live in the Short-Circuit Demo.
  • Why is this Z (blue floating)? Shows that no active output pin is driving the net (for example, an unconnected wire or a Tri-State Buffer whose Enable pin is 0).